Portable electric tool



7 Oct. 3, 1939.

c. DESOUTI'ER 2,174,936

PORTABLE ELECTRIC T091,

5 Sheets-Sheet; -l

Filed April 28, 1937 (er g 1939- c. DESOUTTER PORTABLE ELECTRIC TOOL Filed April 28, 1937 5 Sheets-Sheet 2 NVEA/TM I Oct. 3, 1939. Q DESQUTTER 2,174,936

PORTABLE ELECTRIC TOOL Filed April 28, l937 5 Sheets-Sheet 3 5 I. Al wk I WIIIIIIA IIIA A TTOPNE Y Oct. 3, 1939. Q DESQUTTER 2,174,936

PORTABLE ELECTRIC TOOL Filed April 28, 1937 5Sheets-Sheet 4 HHHL 6a. 3, 1939. c DESQQTTER 2,174,93

PORTABLE ELECTRIC TQOL Filed April 28, 1937 5 Sheets-Sheet 5 Patented Oct. 3, 1939 UNITED STATES PATENT OFFICE 14 Claims.

This invention relates to rotary tool devices carried and applied by hand and particularly to portable electric drills and the like.

It has for its primary object to provide such tools with operating and switching means of novel construction which are certain and efli cient in action.

It has for a. further object to form the operating part as a handor finger-pressed member with a spring return and the switch as a spring toggle switch with extreme positions on each side of a dead centre.

It has for a still further object to provide common spring means for effecting both the return 16 of the operating part and also the operation of the toggle switch.

It has for a'still further object so to mount and position the spring means in relation to the operating part and the switch that upon the release 20 of the hand or finger pressure the operating part and the switch automatically return to the inoperative position.

Another object is to associate a brush holder as a unitary structure with the switch, and a.

5 still further object to associate with this unitary structure the operating part.

As a still further object, the operating part can be made in the form of a trigger to extend on each side of the unitary structure comprised by '30 the brush holder and switch.

Another object is to form the pivots or the like for the parts in one with the said parts.

The above and other objects will appear from the following detailed description given with 35 reference to the accompanying drawings.

In order that the invention may be better understood, it will now be described with reference to the accompanying drawings, in which:

Fig. 1 is a side elevation of the complete tool.

Fig. 2 is an end elevation of Fig. 1 taken'from the chuck end. 1

Fig. 3 is an end elevation of Fig. 1 taken from the handle end.

Fig, 4 shows to a larger scalethe complete tool 45 in sectional elevation.

Fig. 5 is a fragmentary end elevation of a portion of the handle to a still larger scale. 1

Fig. 6 shows in side elevation the unit forme by the operating trigger, switch and brush holder 50 detached and in the off" position and to the same scale as Fig. 5. v

Fig.- 7 is a similar view to Fig. 6 but in section and with the parts in the .on position.

Fig. 8 is a sectional plan taken on the line Y 55 8-8, Fig. '7.

. Fig. 9 is a somewhat similar view to Fig. 4 but partly in outside elevation and with the armature and other parts removed to show the field magnet mounting.

Fig. 10 is an end elevation of the casing. with 5 parts removed, taken from the chuck end but with the gear casing and chuck removed to show the field magnet mounting.

Fig. 11 isa section on the line l|--l I, Fig. 9.

Fig. 12 is a perspective view of the field magnet and its winding removed from the casing.

The tool illustrated in the drawings. which is, one example of a tool constructed according to the invention, is a relatively small portable electric hand drill of the gun or pistol type. It comprises. 15 three main casing portions. The front portion 9 is 'journalled to receive the chuck shaft l0 carrying the chuck II. It also is shaped at the rear to accommodate the gear wheel l2 and the pinion end l3 of the armature shaft I4 which meshes therewith. It is closed by a cover plate I5 which carries one of the bearings 16 for the armature shaft.

i1 is a spring-returned locking pin or plunger the rear end 16 of which is adapted to be in- 25 serted into any one of the apertures IS in the gear wheel l2, when the front of the plunger is pushed inwardly. This immobilises the chuck spindle and allows the chuck to be manipulated by its knurled surface 20 for tool changing purposes.

The shape of the intermediate portion of the casing will be gathered frointhe drawings. It comprises a part 2| of a pistol grip which merges into the main body which latter includes a lower bulged part 22 which at its front is shaped somewhat as a part of a cylinder to engage the lower part of the casing 9. The upper part of the main body 23 is somewhat narrowed, being larger towards the front where it also engages the casing portion 9 and it should be observed that the main body portion from its front narrows 'or tapers rearwardly.

The other body portion is the end member 24, the lower part of which completes the pistol grip, the three body portions giving flush surfaces where they join. The portion 24 is secured to the portion 2| by a screw 25 the head of whichengages in a recess 26 at the rear of the portion 24, the screw engaging in a tapped boss 21in a cross piece connecting the side walls of the portion 2| in an intermediate position as shown in Fig. 4.

The portions 9 and 2| are connected by screws 28 and 25 which also serve to hold the cover plate It in position. Between the cover plate and the The other bearing 34 for the armature shaft is carried by the cross piece 35 which comes adjacent the commutator 36 which is engaged by an upper brush 31, accessible by the removal of the plug 38 screwed into the top portion of the casing 2|, and carried by a conducting liner 39. This latter in turn is mounted in a sleeve is of in sulating material held in position in the socket of the plug 38 by a collar and apertured on one side at 4! for a contact-making pin or plunger carried in a member 42 of insulating material, and the other end of which comes into springpressed contact with a spring tongue 43 of conducting material forming one of the contacts for the winding 44 of the field magnet 45, which is of horseshoe type.

The other brush llB is also carried in a metallic liner 41 mounted in a body of insulating material, as more specifically shown in Figs. 6, i and 8. The shape of this body is best seen from the section of Fig. 7 and it comprises the left-hand side the socket portion for the reception of the liner 41. The lower end oi the socket 48 is formed as a cylindrical recess 49 to receive the turned-over end 50 of the liner 41 and also to accommodate the inner end of a brush-retaining plug 5| shown in position in Fig. 4 where it will be seen it is mounted by means of a screwed exterior in a similarly threaded aperture in the base of the handle. This inner end of the plug 5| also acts as part of a means for retaining the shaped body of insulating material in position. The other side 52 of the said body is recessed on its upper portion to receive the head of a terminal screw 53, the screw engaging in a tapped bore in the body. This screw forms a terminal for the leads 54 and 55 (Fig. 4) the former coming from the exterior through the connector 56 and the latter passing to the other end of the windings 44 of the field magnet 45. The side of this portion 52 has a further recess to accommodate the head 51 of a screw which has a dual purpose. This forms the terminal for a lead 58 from the connector 56 and also acts as a fixing screw for a contact base plate 59, the screw passing through an aperture in the portion 52 of the body to engage with a threaded aperture in the metallic base plate 59. The portions 48 and 52 of the insulating body are connected together by upper and lower members 60 and 5! and these parts enclose a recess or space 62, one wall of which is occupied by the plate 59. This plate is shaped with two depressed portions 63 coming at its sides and forming the fulcrum points for a,

rocking plate or toggle 64 having limbs 65 to engage in the recessed portions 63. This plate 84 is of conducting material and has projecting arms 66 protected by flanged and grooved sleeves 61 of insulating material with which engage the one ends of tension springs 69. The other ends of these springs engage projecting pins or pivots 69 formed integrally. with the arms 19 of a I trigger 1! which straddles the insulating memher as shown .in Figs. 6, 7 and 8. The arms 19 are pivoted to the insulating member on the two sides, that is to say to the lower portion of the partc48 of this insulating member at 12.

The pivots 12 are formed as integral projections of insulating material with the part 48 and in order to engage the arms 10 with these pivot portions they are formed with circular recesses 12 having openings 14. The openings 14 are of such size that they can just pass the pivots 12 but the circular recess 13 is of greater diameter than the pins 12. In order to maintain the parts in position a sleeve 15 is fitted into the space left between the pivot 12 and the circular recess 13. This forms a bush to the pivoting action and retains the trigger in position.

The upper portion of the opening 62 at 16 forms one limiting stop for the toggle 64 and this toggle comes in contact therewith in the"ofi position and as shown in Fig. 6. In this position also stops 11 at the ends of the arms 10 contact with abutments 18 integral with the portion 52 of the insulating body. The other limiting stop for the toggle is comprised by a projection 19 as shown and the toggle comes into contact therewith in the "on position, as shown in Fig. 7.

The liner 41 serves as a retainer for a contact 80. This is formed from strip metal of a springy nature and has a portion 8| which lies in contact with the liner and the upper part of which passes through an aperture 8-2 from the opening 62 into the shaped bore through the portion 48. The end of the strip 8| is bent round at 83 and comes between the flange 50 of the liner 41 and its seating. The other end of the contact is forked at 84, the two limbs of the fork coming beneath projections 85 integral with the stop 19. These projections 85 limit the upward movement of the contact 80 but it can move downwardly to a slight extent. As shown, the contact portion proper is comprised by a curved hump and in its uppermost position, as shown in Fig. 6, it is in position to be engaged by the toggle 64 when this latter is moved to its on position. Just before the toggle reaches this position,however, it makes contact with the contact 80, .slightly depresses this, causing the limbs of the fork to move-away from the projections 85 (as shown in Fig. 7). At the same time there is a slight rubbing action between the metallic toggle 64 and the metallic contact 80. This keeps the contact bright and polished and the electrical circuit proceeding from the terminal 51 passes to the plate 59, then to the toggle, from the toggle through the contact 89, from this contact to the liner 41, and from the liner to the brush.

It should be specifically pointed out that the arms or connections 58 of the toggle 64 form a centre or axis which in the two positions or the toggle remain on the same side of an imaginary line joining the oentres of the pivots 12 and 69.

-whilst in the "on" position this line comes on the other side or the dead centre.

Consequently. it readily willbe seen that the spring means provided has a dual tunction, that is to say it acts as a return spring for the trigger and it acts as the springior the toggle mechanism.

This spring means .further has the properties that when in the "on position the pressure of the finger to retain the contacts is but slight as the centre 69 is approaching the line between the pivots 12 and 99 in this position. Further, although an efllcient contact is made between the toggle 89 and the contact 90 there is no grip or sticktion" between the parts to be overcome,

either in making the contact or breaking the contact.

The body of insulating material straddled by the trigger, as a unitary structure together with the brush, is inserted into position before the portion 24 is secured in position. For this purpose the interior of the lower portion 2| is shaped as shown In Fig. 5 and has an aperture 88 for the passage of the trigger II to the exterior. It also has side walls 81 which come over the ends of the pivots 12 and incidentally preventthe bushes 15 from working out. ,It is secured in position by a plate 88 (Fig. 4) held by screws 89 taking into .threaded bores in the lower extensions of the side walls 81. This plate engages with the projections 98 on the underside of the body of insulating material beneath the screw 51.

The field magnet is o! the horseshoe type with the windings at the upper part of the casing and with the opening between the limbs at the lower part of the casing. This permits the bulk of the casing to be smaller than it another type of field magnet were employed and by the arrangement facilitates the formation of the hand g p, the structure still further having the bulk reduced by locating one of the brushes 46 and its holder within the handle.

If the necessary machining on the interior of the casing follows closely the contour of 'the limbs of the field magnet, when machining the interior or the casing it is necessary that this casing should be set up on two separate occasions as turning etc. has to take place about two axes, i.'e. that of the'armature shaft (which corresponds to the interior curvature of the limbs of the magnet) and that of the curvature of the exterior of the limbs of the magnet. To obviate this double setting up, the-inside of the casing is only machined where required about the axis of the armature shaft and the limbs of the magnet are formed or provided with shaped or projecting portions to register with the interior machining. r

This will be seen clearly in Fig. 12 where each limb 9I ot the fieldmagnet is made up from the required number of. laminations riveted together at 92 and 93 and has three projecting portions 94, 95 and 98 (the portion 94 not showing on one limb). It .should be pointed out that the projections 95 come towards the chuck end of the tool and these,

on their exterior face with the machined portions 91 on the interior of. the casing. Similarly, the

projecting portions 94 come towards the chuck end and register with machined portions 98 in the casing. Towards the handle end oi. the tool, however, the projections 98 have somewhat less radial extent and consequently it is possible to reduce the diameter of this portion of the easing adjacent thereto as seen clearly in Figs. 1, 4 and 9. This reduction in the diameter of the casing in this position gives greater accommodation for the fingers of the hand and to a large extent retains the maximum advantage of using a horseshoe form of magnet, without the disadvantage of the double setting up for the machining of the interior of the casing.

The interiorv ot the casing is formed with ribs 99 which are stepped at I88 'to form stops axially to position the field magnet. Longitudinally also the ribs 99 contact with the upper portions of the laminations to register the field magnet in position.

Similarly, other ribs I8I are'provided extendingtowards the handle to act as limiting stops adapted manually to be as shown in Fig. 10, register.

for

, the insertion of the fleld'magnet. Finally, other ribs I82 are provided, extending towards the handle, with which the lower ends of the rear lamination contact. 9

- Between the machined portion 81 and the rib I42 what may be regarded as an extension or the, rib I82 projects towards the chuck end in the form of a step I88 to cooperate with or just clear the projection 98.

' When the field magnet is inserted in position it is axially retained by the spring I88 which can enter a groove I84 in the interior of the casing.

Fig. 12 also illustrates the spring contact 48 which'leads to one end of the windings 44, being the lead to the other end of the windings.

The invention'is not limited to the precise forms or details of construction described, as these may be varied to suit particular cases.

whatI claim and desire to secure by Letters Patent of theUnited States of America is:

1. In an electrically driven tool of the character described, means for starting and stopping the tool comprising a rocking toggle switch member of conductive material adapted to be brought into the on'or ofl!" positionya movable trigger normally maintained in the oif position but brought into the on! position, a single common spring means operatively connected to both the toggle switch member and the trigger to hold the toggle switch member in either the on or of!" position and automatically to return the said toggle switch member and the trigger on manual release of the latter to the oil position and a lead coacting with the switch member at the point about which said switch rocks.

2. -In anelectrically driven tool of the character described, an outer casing, an electric motor located in said casing, a toggle switch including a 'casing of insulating material, electrical conducting members and a rocking toggle switch member of conducting material adapted to be brought into the on" or off position, a holder for one of the brushes of the motor formed as a unitary structure with the casing of the switch, a movable trigger normally maintained in the "ofi" position but adapted manually to be brought into the on position, common spring means operatively connected to both the toggle switch outer casing.

3. In an electrically driven tool of the character described, ah outer casing having a trigger aperture, an electric motor located in said casing, a toggle switch including a casing of insulating material, electrical conducting members anda rocking toggle switch member of com ducting material adapted to be. brought into the on or oil position, a holder for one of the brushes of the motor formed as a unitary structure with the casing of the switch, a pivotally mounted trigger comprised by two arms straddling the unitary structure formed by the switch casing and brush holder and connected together at the trontby the trigger part proper which is adapted to emerge through said trigger aperture in the outer casing, the said trigger being normally maintained in the ofi" position but adapted manually to be brought into the on position, common spring means operatively connected to both the toggle switch member and the trigger to hold the toggle switch member in either the on or ofl position and automatically to return the said toggle switch member and the trigger on manual release of the latter to the ofi position, and means for mounting the said unitary structure in position in the outer casing.

4. An electrically driven tool of the character described and as set forth in claim 3, including two conducting members mounted in the insulating casing of the toggle switch, conducting means carried by the brush holder for making electrical contact with the brush carried thereby, means for electrically connecting the said conducting means to one of the conducting members of the switch, electricalterminal means carried by the switch casing and in connection with the other conducting member of the switch, and means for rockingly mounting the rocking toggle switch member 7 in the said other conducting member of the switch.

5. An electrically driven tool of the character described and as set forth in claim 3, including in the unitary structure formed by the switch casing and brush holder integral projecting pivots for mounting the arms of the trigger.

6. An electrically driven tool of the character described and as set forth in claim 3, including in the unitary structure formed by the switch casing and brush holder integral projecting pivots for mounting the arms of the trigger, the said arms having circular apertures of greater diameter than the pivots opening to the exterior by slots of the same diameter as the pivots to take around the pivots, and interposed filling bushings in the slotted apertures and around the pivots.

7. An electrically driven tool of the character described and as set forth in claim 3, including two conducting members mounted in the insulating casing of the toggle switch, a conducting liner in the brush holder, an extension of one of the conducting members of the switch held between a portion of the brush holder and said liner and in electrical contact with the said liner, electrical terminal means carried by the switch casing and in connection with the other conducting member of the switch, and means for rockingly mounting the rocking toggle switch member in said other conducting member of the switch.

8. An electrically driven tool of the character described and as set forth in claim 3, including two conducting members mounted in the insulating casing of the toggle switch, one being constituted by bent springy strip metal, a conducting liner in the brush holder, one end of the springy strip being held between a portion of the brush holder and said liner and in electrical contact with the said liner, electrical terminal 'means carried by the switch casing and in connection with the other conducting member of the switch, and means for rockingly mounting the rocking toggle switch member in the said other conduct-- ing member of the switch.

9. An electrically driven tool of the character described and as set forth in claim 3, including two conducting members mounted in the insulating casing of the toggle switch, one being constituted by bent springy strip metal, a conducting liner in the brush holder, one end of the.

springy strip being held between a portion of the brush holder and said liner and in electrical contact with the said liner, electrical terminal means carried by the switch casing and in connection prising a rocking toggle switch having a body oi insulating material, a brush holder formed integrally with the said body and at one side thereof, terminal means secured to the other side of said body, the said sides being connected by upper and lower members leaving a space surrounded by the said sides and upper and lower members, a conducting member for the switch secured to one side bounding said space and having depressions to constitute fulcrum bearings, a rocking toggle member of conducting material located in said space and mounted to rock in said depressions, a bent springy strip of conducting metal forming the other conducting member of the switch, a conducting liner in'the brush holder, one end of the said springy strip being secured between the conducting liner and the brush holder and in electrical connection with the said liner, the other end of the springy strip coming in the path of the rocking toggle switch me ber as it approaches its on position to make spring contact therewith, a pivotally mounted trigger comprised by two arms straddling and pivoted to the structure formed by the switch casing and brush holder and connected together at the front by the trigger part proper, said trigger being normally maintained in the off position but adapted manually movement of the parts being such that in the off position of the trigger the rocking toggle switch member is held in the off position, on

one side of its dead center line by the springs whilst in the on position of the trigger the rocking toggle switch member is held in the on position on the other side of its dead center line by said springs, the tension of the springs in all positions tending automatically to bring the trig: ger to or maintain it in the off position.

11. An electrically driven tool of the character described and as claimed in claim 10, including an outer casing, an electric motor located in said casing, and fixed and movableabutments in said outer casing to locate and hold in position the said unitary structure forming the means'for starting and stopping the tool. 4 V

12. An electrically driven tool of the character described and as claimed in claim 10, including an outer casing, a hollow pistol grip forming part of said casing and having a trigger aperture, an electric motor of the horseshoe type located in said casing, and fixed and movable abutments in the said hollow pistol grip to locate and hold in position the said unitary structure forming the means tor starting and stopping the tool, the trigger part proper emerging through said aperture in the front of the hollow pistol grip.

13. An electrically driven tool or the character described and as claimed in claim 10, including an outer casing comprising front, intermediate and rear parts, a chuck shaft and reduction driving gearing carried by and accommodated in the said front part, an electric motor comprising a horseshoe magnet with windings, a co-operating armature with shaft, and an upper brush holder located in the saidintermediate part, the armature shaft being operatively connected with the said reduction driving gearing, and the said intermediate part forming part of a hollow apertured pistol grip, the rear part of the outer casing being formed as the remainder of the hollow pistol grip, and fixed and movable abutm'ents in the said hollow pistol grip to locate and hold in position the unitary structure forming the means for starting and stopping the tool and including a holder for the lower brush, the trigger part proper emerging through said aperture in 1 the front of the hollow pistol grip.

14. An electrically driven tool of the character described and as claimed in claim 10, including an outer casing comprising front, intermediate and rear parts, a chuck shaft and reduction driving gearing carried by and accommodated in the said front part, an electric motor comprising a horseshoe magnet with windings, a co-operating armature with shaft, and an upper brush ho'lder located in the said intermediate part, the armature shaft being operatively connected with the said reduction driving gearing, and the said intermediate part forming part of a hollow apertured pistol grip, an insulating sleeve having an opening carried by the upper brush holder, a

' conducting liner for the said insulating sleeve,

spring contact-making means between the said liner and the windings of the electro-magnet and operative through said opening in the insulating sleeve, the rear part of the outer casing being formed as the remainder of the hollow pistol grip, and fixed and movable abutments in the said hollow pistol grip to locate and hold in position the unitary structure forming the means for starting and stopping the tool and including a holder for the lower brush, the trigger part proper emerging through said aperture in the front of the hollow pistol grip.

CHARLES DESOU'ITER.' 

